JP4010280B2 - Fuel injection amount control device for internal combustion engine - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a fuel injection amount control device for an internal combustion engine, and more particularly to a fuel injection amount for an internal combustion engine that determines a fuel injection amount in accordance with an amount of fuel adhering to a member constituting an intake passage of the internal combustion engine (fuel attachment amount). The present invention relates to a quantity control device.
[0002]
[Prior art]
Conventionally, the amount of fuel adhering to a member constituting the intake passage such as an intake passage wall surface or the back surface of the intake valve (hereinafter referred to as “intake passage constituent member”) is represented by a fuel behavior simulation model (“fuel dynamic characteristics” (Hereinafter also referred to as “model”, “fuel adhesion model”, or “fuel behavior model”). 2. Description of the Related Art There is known a fuel injection amount control device for an internal combustion engine that determines a fuel injection amount for matching an air / fuel ratio of an engine with a target air / fuel ratio (see, for example, Patent Document 1).
[0003]
[Patent Document 1]
Japanese Patent No. 2754744 (page 3, FIG. 3)
[0004]
According to the fuel behavior simulation model in this type of apparatus, as can be understood from FIG. 7, the fuel adhesion amount fw (k + 1) after injecting the fuel amount of fi (k) is It is obtained by the equation (1).
[0005]
[Expression 1]
fw (k + 1) ＝ R ・ fi (k) ＋ P ・ fw (k)… (1)
[0006]
In the above equation (1), fw (k) is the fuel adhesion amount before injecting the fuel amount of fi (k), and P is one intake stroke among the fuels already adhered to the intake passage components. The ratio of the fuel that remains attached to the intake passage constituent member later (fuel residual ratio), and R is the ratio of the fuel that adheres directly to the intake passage constituent member of the injected fuel (fuel attachment ratio).
[0007]
On the other hand, the amount of fuel sucked into the cylinder (combustion chamber) out of the fuel of the fuel injection amount fi (k) this time becomes (1-R) · fi (k), and the amount of fuel already attached ( Of the fuel adhesion amount fw (k), the amount of fuel sucked into the cylinder is (1−P) · fw (k). Therefore, if fc (k) is the amount of fuel (required fuel amount) required for the air-fuel ratio of the air-fuel mixture sucked into the combustion chamber in the current intake stroke to match the predetermined target air-fuel ratio, the same mixture In order to set the air / fuel ratio of the fuel to the target air / fuel ratio, the current fuel injection amount fi (k) may be obtained so that the following equation (2) is satisfied.
[0008]
[Expression 2]
fc (k) = (1-R) ・ fi (k) + (1-P) ・ fw (k) (2)
[0009]
Therefore, in reality, the current fuel injection amount fi (k) may be obtained from equation (3) obtained by modifying equation (2). This equation (3) represents an inverse model of the fuel behavior simulation model.
[0010]
[Equation 3]
fi (k) = {fc (k) − (1-P) · fw (k)} / (1-R) (3)
[0011]
By the way, the fuel residual rate P and the fuel adhesion rate R are parameters called fuel behavior parameters. The fuel behavior parameter is generally determined as follows and used in actual operation. First, the engine is operated in a steady operation state in which the operation state parameters such as the intake air amount (or throttle valve opening), the engine rotation speed, and the engine coolant temperature are maintained constant, and the above equation (1) and ( The fuel injection amount is determined by equation (3). Next, fuel of the determined fuel injection amount is injected and the air-fuel ratio at that time is measured, and the fuel behavior parameter is changed so that the actually measured air-fuel ratio matches the target air-fuel ratio. When the actually measured air-fuel ratio matches the target air-fuel ratio, the relationship between the fuel behavior parameter and the engine operating state parameter at that time is obtained, and the relationship is stored in the ROM. In actual operation, the actual operation state parameter is measured, and the fuel behavior parameter at that time is determined using the operation state parameter and the relationship stored in the ROM.
[0012]
[Problems to be solved by the invention]
However, the engine is not only operated in a steady operation state where the operation state parameter is constant, but, for example, a transient operation state in which the throttle valve opening is suddenly changed and the operation state parameter fluctuates rapidly, or a fuel injection stop state The operation is performed even in a transient operation state immediately after the fuel injection is restarted. For this reason, if the fuel injection amount is determined using the fuel behavior parameter determined as described above, the fuel behavior parameter may not be appropriate in the transient operation state, and therefore the determined fuel injection amount is inappropriate. Become. As a result, there is a problem that the actual air-fuel ratio of the engine deviates from the target air-fuel ratio and unburned components and nitrogen oxides in the exhaust gas increase.
[0013]
[Outline of the present invention]
The inventor of the present invention examined the amount of fuel adhesion in more detail in order to solve such a problem. As a result, even if the engine operating state parameter is the same, the inventor is more likely to adhere the injected fuel to the intake passage component when the fuel adhesion amount is large than when the fuel adhesion amount is small and It was found that the fuel adhering to the intake passage constituting member is more difficult to evaporate. Therefore, the present inventor utilizes the fact that the fuel behavior parameters (the fuel residual rate and the fuel adhesion rate) are changed depending on the fuel adhesion amount, and that the fuel adhesion amount becomes a constant amount in the steady operation state, While determining the amount of fuel adhering when assuming that the engine is in steady operation (steady fuel adhering amount), depending on whether the estimated fuel adhering amount is larger or smaller than the steady state fuel adhering amount, The present invention has been reached in which the fuel behavior parameters (fuel residual rate and fuel adhesion rate) adapted in the steady operating state are changed.
[0016]
Book According to the invention Burning The fuel injection amount control device is used in a simulation model that represents the behavior of fuel injected from the fuel injection means, and “a fuel adhesion rate that is a ratio at which fuel injected from the fuel injection means adheres to members constituting the intake passage” And a fuel behavior parameter used in the simulation model, including “a fuel residual ratio that is a ratio in which the fuel adhering to the member constituting the intake passage remains without being sucked into the cylinder”, and the engine is in a steady operation state And a fuel behavior parameter determining means for predetermining the relationship between the operation state parameter representing the operation state of the engine when the engine is in the state and determining the fuel behavior parameter based on the stored relationship and the actual operation state parameter It has.
[0017]
Thereby, the fuel behavior parameter is determined according to the actual operation state parameter so as to be an optimum value when the engine is in the steady operation state.
[0018]
In addition, this fuel injection amount control device The amount of fuel evaporated from the fuel adhering to the member constituting the intake passage and sucked into the cylinder and the amount of fuel adhering to the member constituting the intake passage from the fuel injected from the fuel injection means Is the amount of fuel adhering to the members constituting the intake passage in order to equalize Fuel adhesion amount same Constant before and after fuel injection from the fuel injection means To become Under the assumption , A steady-state fuel adhesion amount estimating means for estimating a steady-state fuel adhesion amount that is a fuel adhesion amount in a steady operation state using the determined fuel behavior parameter and the simulation model, the determined fuel behavior parameter, and the Adhering to a member constituting the intake passage for each injection from the fuel injection means using a simulation model is doing The instantaneous fuel adhesion amount estimating means for estimating an instantaneous fuel adhesion amount that is an instantaneous value of the fuel adhesion amount that is the amount of fuel, and the determination is made according to a comparison result between the instantaneous fuel adhesion amount and the steady-state fuel adhesion amount. Fuel behavior parameter correction means for correcting the fuel behavior parameter.
[0019]
The fuel injection amount control device assumes that the fuel adhesion amount is constant before and after fuel injection from the fuel injection means. That is, the amount of fuel evaporated from the fuel adhering to the member constituting the intake passage and sucked into the cylinder and the fuel injected from the fuel injection means adhere to the member constituting the intake passage Under the assumption that the amount of Using the determined fuel behavior parameter and the simulation model, a steady-state fuel deposition amount that is a fuel deposition amount in a steady operation state is estimated. This The fuel adhesion amount when there is no need to correct the fuel behavior parameter determined based on the stored relationship is obtained as the steady-state fuel adhesion amount.
[0020]
At the same time, the fuel injection amount control device uses the determined fuel behavior parameter and the simulation model to determine the amount of fuel that adheres to the member constituting the intake passage for each injection from the fuel injection means. The instantaneous fuel adhesion amount that is the instantaneous value of the adhesion amount is estimated. That is, the fuel adhesion amount that changes in accordance with the actual fuel adhesion amount is obtained as the instantaneous fuel adhesion amount.
[0021]
Then, the fuel injection amount control device corrects the determined fuel behavior parameter according to a comparison result between the instantaneous fuel attachment amount and the steady-state fuel attachment amount. In this case, the fuel behavior parameter correction means is configured to correct the fuel behavior parameter so that the fuel behavior parameter increases as the instantaneous fuel attachment amount increases with respect to the steady-state fuel attachment amount. Is preferable.
[0022]
The fuel injection amount control device applies the corrected fuel behavior parameter and the required fuel amount required for the engine to the inverse model of the simulation model, and the fuel injection that is the amount of fuel to be injected from the fuel injection means The amount is determined, and the fuel injection amount of fuel is injected from the fuel injection means.
[0023]
As a result, the fuel behavior parameter becomes a more appropriate value regardless of whether the engine is in a steady operation state or a transient operation state, so the fuel injection amount determined by the inverse model of fuel behavior is appropriate. Value. Therefore, this fuel injection amount control device can make the actual air-fuel ratio of the engine substantially coincide with the target air-fuel ratio, and can reduce unburned components and nitrogen oxides in the exhaust gas.
[0024]
By the way, if the amount of fuel adhering to the intake passage constituting member becomes excessive, a part of the adhering fuel may flow into the cylinder in a liquid state (so-called liquid dripping phenomenon occurs). Therefore, the instantaneous fuel adhering amount estimation means adheres to the intake passage constituting member when the instantaneous fuel adhering amount estimated using the determined fuel behavior parameter and the simulation model exceeds a predetermined threshold value. It is determined that part of the fuel has flowed into the cylinder in a liquid state.
[0025]
Further preferably, the instantaneous fuel adhering amount estimation means estimates the amount of fuel flowing into the cylinder in a liquid state (that is, the amount of inflowing liquid fuel) based on an operating state parameter of the engine, and determines the determined fuel An amount obtained by subtracting the estimated inflow liquid fuel amount from the instantaneous fuel adhesion amount estimated using the behavior parameter and the simulation model is estimated as a new instantaneous fuel adhesion amount.
[0026]
According to this, even when a part of the adhered fuel flows into the cylinder in a liquid state, the fuel adhesion amount is estimated with high accuracy, so that the fuel behavior parameter is also determined with high accuracy.
[0027]
In this case, when the instantaneous fuel adhering amount estimation means determines that a part of the fuel adhering to the member constituting the intake passage flows into the cylinder in a liquid state, it adheres to the member constituting the intake passage. It is preferable to further include an adhering fuel inflow suppressing means that operates to suppress the flowing fuel from flowing into the cylinder in a liquid state.
[0028]
The estimation accuracy of the inflowing liquid fuel amount is inferior to the estimation accuracy of the fuel adhesion amount in a state where a part of the fuel does not flow into the cylinder in a liquid state. Therefore, the fuel injection amount can be made a more appropriate amount by avoiding a situation in which a part of the fuel flows into the cylinder in the liquid state by the attached fuel inflow suppression means.
[0029]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of a fuel injection amount control device for an internal combustion engine according to the present invention will be described below with reference to the drawings.
[0030]
(First embodiment)
FIG. 1 shows a schematic configuration of a system in which the fuel injection amount control device according to the first embodiment is applied to a four-cycle spark ignition type multi-cylinder internal combustion engine 10. FIG. 1 shows only a cross section of a specific cylinder, but the other cylinders have the same configuration.
[0031]
The internal combustion engine 10 includes a cylinder block portion 20 including a cylinder block, a cylinder block lower case, an oil pan, and the like, a cylinder head portion 30 fixed on the cylinder block portion 20, and a gasoline mixture to the cylinder block portion 20. An intake system 40 for supplying and an exhaust system 50 for releasing exhaust gas from the cylinder block 20 to the outside are included.
[0032]
The cylinder block unit 20 includes a cylinder 21, a piston 22, a connecting rod 23, and a crankshaft 24. The piston 22 reciprocates in the cylinder 21, and the reciprocating motion of the piston 22 is transmitted to the crankshaft 24 through the connecting rod 23, whereby the crankshaft 24 rotates. The heads of the cylinder 21 and the piston 22 form a combustion chamber 25 together with the cylinder head portion 30.
[0033]
The cylinder head portion 30 includes an intake port 31 communicating with the combustion chamber 25, an intake valve 32 that opens and closes the intake port 31, an intake camshaft that drives the intake valve 32, and a phase angle and lift amount of the intake camshaft are continuously provided. Variable intake timing device 33 to be changed, actuator 33a of variable intake timing device 33, exhaust port 34 communicating with combustion chamber 25, exhaust valve 35 for opening and closing exhaust port 34, exhaust camshaft 36 for driving exhaust valve 35, An ignition plug 37, an igniter 38 including an ignition coil that generates a high voltage to be applied to the ignition plug 37, and an injector (fuel injection means) 39 for injecting fuel into the intake port 31 are provided.
[0034]
The injector 39 is connected to the fuel pressure adjusting means 39a. The fuel pressure adjusting means 39a communicates with an intake passage downstream of the throttle valve 43 through a communication passage (not shown) and is connected to a fuel pump (not shown). The fuel pressure adjusting means 39a includes an electromagnetically driven linear control valve (not shown) that is driven by an external drive signal. Thus, the fuel pressure adjusting means 39a can maintain the fuel pressure (fuel injection pressure) at a pressure higher than the intake pipe pressure by the differential pressure Psa, and can change the differential pressure Psa according to the drive signal. Yes.
[0035]
The intake system 40 is provided in an intake pipe 41 including an intake manifold that communicates with the intake port 31 and forms an intake passage together with the intake port 31, an air filter 42 provided at an end of the intake pipe 41, and the intake pipe 41. A throttle valve 43 and a swirl control valve (hereinafter referred to as “SCV”) 44 that change the opening cross-sectional area of the intake passage are provided. The throttle valve 43 is rotationally driven in the intake pipe 41 by a throttle valve actuator 43a made of a DC motor.
[0036]
The SCV 44 is rotatably supported with respect to the intake pipe 41 at a position downstream of the throttle valve 43 and upstream of the injector 39, and is rotated by an SCV actuator 44a formed of a DC motor. The swirl is generated in the combustion chamber 25 by closing a straight port (not shown) when rotated by the SCV actuator 44a.
[0037]
Members constituting the intake passage such as the intake pipe 41 including the intake manifold, the intake port 31 and the intake valve 32 are referred to as “intake passage constituent members”.
[0038]
The exhaust system 50 includes an exhaust manifold 51 communicating with the exhaust port 34, an exhaust pipe 52 connected to the exhaust manifold 51, a catalytic converter (three-way catalyst device) 53 interposed in the exhaust pipe 52, an EGR gas passage 54, and EGR. An EGR valve 55 is provided in the gas passage 54 to open and close the EGR gas passage 54. The exhaust port 34, the exhaust manifold 51, and the exhaust pipe 52 constitute an exhaust passage.
[0039]
The EGR gas passage 54 is a communication passage that communicates the exhaust port 34 (exhaust passage) and the intake passage downstream of the throttle valve 43 and upstream of the injector 39. When the EGR valve 55 is open, the EGR gas passage 54 introduces a part of the exhaust gas that passes through the exhaust passage into the intake passage due to the negative pressure in the intake pipe 41.
[0040]
On the other hand, this system includes a hot-wire air flow meter 61, an intake air temperature sensor 62, an atmospheric pressure sensor (a throttle valve upstream pressure sensor) 63, a throttle position sensor 64, an SCV opening sensor 65, a cam position sensor 66, a crank position sensor 67, A water temperature sensor 68, an air-fuel ratio sensor 69, and an accelerator opening sensor 71 are provided.
[0041]
The air flow meter 61 outputs a signal corresponding to the mass flow rate Ga of the intake air flowing through the intake pipe 41. The intake air temperature sensor 62 detects the temperature of the intake air and outputs a signal representing the intake air temperature THA. The atmospheric pressure sensor 63 detects the pressure upstream of the throttle valve 43 (that is, atmospheric pressure) and outputs a signal indicating the throttle valve upstream pressure Pa.
[0042]
The throttle position sensor 64 detects the opening (throttle valve opening) of the throttle valve 43 and outputs a signal representing the throttle valve opening TA. The SCV opening sensor 65 detects the opening of the SCV 44 and outputs a signal representing the SCV opening θiv.
[0043]
The cam position sensor 66 generates a signal (G2 signal) having one pulse every time the intake camshaft rotates 90 ° (that is, every time the crankshaft 24 rotates 180 °). The crank position sensor 67 outputs a signal having a narrow pulse every time the crankshaft 24 rotates 10 ° and a signal having a wide pulse every time the crankshaft 24 rotates 360 °. This signal represents the engine speed NE.
[0044]
The water temperature sensor 68 detects the temperature of the cooling water of the internal combustion engine 10 and outputs a signal representing the cooling water temperature THW. The air / fuel ratio sensor 69 outputs a signal corresponding to the air / fuel ratio A / F in the exhaust gas flowing into the catalytic converter 53. The accelerator opening sensor 71 outputs a signal representing the accelerator pedal operation amount Accp operated by the driver.
[0045]
The electric control device 80 includes a CPU 81 connected to each other by a bus, a ROM 82 in which programs executed by the CPU 81, tables (maps, functions), constants, and the like are stored in advance, a RAM 83 in which the CPU 81 temporarily stores data as necessary, The microcomputer includes a backup RAM 84 that stores data while the power is turned on and retains the stored data while the power is shut off, and an interface 85 including an AD converter.
[0046]
The interface 85 is connected to the sensors 61 to 69 and 71, and supplies signals from the sensors 61 to 69 and 71 to the CPU 81, and in response to instructions from the CPU 81, the actuator 33a, the igniter 38, Drive signals are sent to the injector 39, the fuel pressure adjusting means 39a, the throttle valve actuator 43a, and the SCV actuator 44a.
[0047]
(Operation)
Next, the operation of the fuel injection amount control device configured as described above will be described. When the crank angle of the engine 10 reaches a predetermined angle that is a predetermined crank angle before the intake top dead center of the first cylinder (for example, the crank angle immediately before reaching the intake stroke at BTDC 90 °) in FIG. The fuel injection control routine is started from step 200. The CPU 81 executes the same routine as that shown in FIG. 2 for each of the other cylinders at the same timing.
[0048]
Next, the CPU 81 proceeds to step 205 and uses the intake air flow rate Ga detected by the air flow meter 61 for the intake air flow rate Q sucked into the combustion chamber 25 of the first cylinder according to the following equation (4). Ask. In the following formula (4), α is an arbitrary coefficient from 0 to 1.
[0049]
[Expression 4]
Q = α · Q + (1−α) · Ga (4)
[0050]
Next, the CPU 81 proceeds to step 210 and multiplies the value obtained by dividing the intake air flow rate Q by the engine rotational speed NE by a predetermined coefficient k1, and is sucked into the combustion chamber 25 of the first cylinder about to reach the intake stroke. In step 215, the air quantity KL is obtained, and the air quantity KL is divided by the target air-fuel ratio Abyfref (for example, 14.7 which is the theoretical air-fuel ratio) to obtain the air-fuel mixture sucked into the combustion chamber 25 of the first cylinder. The required fuel amount fc (k), which is the amount of fuel necessary to make the air-fuel ratio of the target air-fuel ratio Abyfref, is calculated. The target air-fuel ratio Abyfref is changed according to engine operating state parameters such as the throttle valve opening TA, the engine speed NE, and the coolant temperature THW.
[0051]
Next, the CPU 81 proceeds to step 220, in which a table (function) stored in advance in the ROM 82 that defines the relationship between the engine operating state parameter consisting of the engine speed NE, the air amount KL, and the coolant temperature THW and the fuel residual rate Ptj. ) Based on f1, the current engine speed NE, the air amount KL obtained as described above, and the cooling water temperature THW (current operating state parameter) detected by the water temperature sensor 68 at the present time, the current fuel residual ratio Ptj Ask for.
[0052]
Similarly, in the subsequent step 225, the CPU 81 stores a table (function) g1 stored in advance in the ROM 82 that defines the relationship between the engine speed NE, the air amount KL, the coolant temperature THW, and the fuel adhesion rate Rtj, The fuel deposition rate Rtj at the present time is obtained based on the engine rotation speed NE, the air amount KL obtained as described above, and the cooling water temperature THW detected by the water temperature sensor 68 at the present time.
[0053]
Here, a method for determining the table f1 and the table g1 will be described. First, the engine is operated in a steady operation state in which the operation state parameters such as the intake air flow rate Q (throttle valve opening TA), the engine speed NE, and the engine coolant temperature THW are kept constant, and an appropriate fuel residual ratio Ptj Then, the fuel adhesion amount and the fuel injection amount are determined by the fuel adhesion rate Rtj and the above equations (1) and (3).
[0054]
Next, the fuel of the determined fuel injection amount is injected and the air-fuel ratio at that time is actually measured. Then, the same experiment was repeated by changing the fuel residual ratio Ptj and the fuel adhesion ratio Rtj (that is, the fuel behavior parameter), and the fuel residual ratio Ptj and the fuel adhesion ratio when the measured air-fuel ratio coincides with the target air-fuel ratio. The relationship between Rtj and the engine operating state parameter at that time is determined as a table f1 and a table g1, respectively.
[0055]
The cooling water temperature THW is used as an operation state parameter representing the temperature of the intake passage constituent member, and can be replaced with the temperature of the intake valve 32 or the intake pipe wall surface temperature (or an estimated value of these temperatures). Further, the fuel residual rate Ptj and the fuel adhesion rate Rtj may be determined in accordance with the SCV opening degree θiv detected by the SCV opening degree sensor 65 and / or the timing VT of the variable intake valve.
[0056]
Next, the CPU 81 proceeds to step 230 to obtain a ratio r (r = fw (k) / fwtj (k)) of the instantaneous fuel adhesion amount fw (k) to the steady-state fuel adhesion amount fwtj (k). The constant fuel deposition amount fwtj (k) is an estimated value of the fuel deposition amount when it is assumed that the engine 10 is in a steady operation state, and is obtained in Step 260 and Step 265 described later. In addition, the instantaneous fuel adhesion amount fw (k) is the fuel adhesion rate Rtj obtained in the step 225, the fuel residual rate Ptj obtained in the step 220, and the instantaneous fuel obtained when the routine was executed last time. This is a value corresponding to the fuel deposition amount at that time obtained based on the fuel deposition amount fw (k), and is obtained in step 250 and step 255 described later.
[0057]
Next, the CPU 81 proceeds to step 235, corrects the fuel residual rate Ptj based on the ratio r to determine the corrected fuel residual rate P, and corrects the fuel adhesion rate Rtj based on the ratio r to correct the corrected fuel residual rate Ptj. The fuel adhesion rate R is determined.
[0058]
More specifically, when the CPU 81 proceeds to step 235, it starts the routine shown in FIG. 3 from step 300, proceeds to step 305, and proceeds to step 305 to a first predetermined value (in this example, the ratio r is smaller than “1”). 0.9) or less. If the ratio r is equal to or less than the first predetermined value, the CPU 81 makes a “Yes” determination at step 305 and proceeds to step 310 to correct the remaining fuel ratio Ptj by a predetermined coefficient kP1 smaller than “1”. 2 is obtained, and the fuel adhesion rate Rtj is multiplied by a predetermined coefficient kR1 smaller than “1” in step 315 to obtain a corrected fuel adhesion rate R. Proceed to step 240.
[0059]
Thus, the ratio r being smaller than the first predetermined value means that the actual fuel adhesion amount is the fuel adhesion amount when the engine is in a steady operation state (in other words, the relationship between the operating state parameter and the fuel residual rate Ptj). This means that the amount of fuel adhering to the table f1 and the operating state parameter and the table g1 which is the relationship between the fuel adhering rate Rtj and the fuel adhering rate Rtj is considerably smaller.
[0060]
Accordingly, the CPU 81 obtains the corrected fuel residual rate P by correcting the fuel residual rate Ptj obtained from the operation state parameter at that time and the table f1 to be small by the above steps 305 to 315, and The corrected fuel adhesion rate R is obtained by correcting the fuel adhesion rate Rtj obtained from the current operating state parameter and the table g1 to be small.
[0061]
On the other hand, when the ratio r is larger than the first predetermined value, the CPU 81 makes a “No” determination at step 305 and proceeds to step 320, where the ratio r is a second predetermined value larger than “1” (here, 1.1). It is determined whether it is above.
[0062]
If the ratio r is equal to or greater than the second predetermined value, the CPU 81 makes a “Yes” determination at step 320 and proceeds to step 325 to correct by multiplying the fuel residual ratio Ptj by a predetermined coefficient kP2 greater than “1”. 2 is obtained, and the fuel adhesion rate Rtj is multiplied by a predetermined coefficient kR2 greater than “1” in step 330 to obtain the corrected fuel adhesion rate R. Proceed to step 240.
[0063]
Thus, the ratio r being larger than the second predetermined value means that the actual fuel adhesion amount is considerably larger than the fuel adhesion amount when the engine is in a steady operation state. Therefore, the CPU 81 corrects the fuel residual rate Ptj so as to increase the fuel residual rate Ptj obtained from the operation state parameter at that time and the table f1 in steps 320 to 330, and the corrected fuel residual rate P And the corrected fuel adhesion rate R is obtained by correcting the fuel adhesion rate Rtj so as to increase the fuel adhesion rate Rtj obtained from the operation state parameter at that time and the table g1.
[0064]
On the other hand, if the ratio r is larger than the first predetermined value and smaller than the second predetermined value, the CPU 81 makes a “No” determination in both steps 305 and 320 and proceeds to step 335 and step 340, where the residual fuel ratio Ptj The fuel adhesion rate Rtj is stored (set) as the corrected fuel residual rate P and the corrected fuel adhesion rate R.
[0065]
As described above, as the ratio r increases (that is, as the fuel adhesion amount (instantaneous fuel adhesion amount) increases), the fuel adhesion rate and the fuel residual rate increase, and as the ratio r decreases, the fuel adhesion rate and the fuel residual rate decrease. When the amount of fuel adhering is small, the smaller the amount of fuel adhering to the intake passage constituent member than when the fuel is adhering, the contact area (heat receiving area) of the adhering fuel to the intake passage constituent member with respect to the volume of the adhering fuel Is relatively large, it is presumed that this is because the fuel is likely to evaporate from the intake passage component (it is difficult to adhere and remain).
[0066]
Next, the CPU 81 injects fuel behavior parameters (fuel residual rate P and fuel adhesion rate R) corrected in step 240 of FIG. 2 from a fuel behavior simulation model (injector 39) expressed by the following equation (5). The fuel amount to be injected into the first cylinder (fuel injection amount) fi (k) is determined by applying to the inverse model of the simulation model representing the behavior of the fuel.
[0067]
[Equation 5]
fi (k) = {fc (k) − (1-P) · fw (k)} / (1-R) (5)
[0068]
Next, the CPU 81 proceeds to step 245, and sends an instruction signal to the injector 39 so that fuel of the determined fuel injection amount fi (k) is injected from the injector 39 corresponding to the first cylinder. In step 250, the CPU 81 estimates and updates the instantaneous fuel adhesion amount fw (k + 1) according to the following equation (6). In step 255, the CPU 81 calculates the instantaneous fuel adhesion amount fw (k + 1) for the next main routine. Is stored as the instantaneous fuel adhesion amount fw (k)
[0069]
Equation (6) is a forward model of a fuel behavior simulation model that expresses the dynamic behavior of fuel using the fuel behavior parameters determined by the operating state parameters of the engine. The instantaneous fuel adhesion amount fw (k) is an amount corresponding to the fuel adhesion amount of the first cylinder before fuel injection to the first cylinder this time. The instantaneous fuel adhesion amount fw (k + 1) corresponds to the fuel adhesion amount of the first cylinder after fuel injection to the first cylinder (that is, the fuel adhesion amount before fuel injection to the first cylinder next time). It is.
[0070]
[Formula 6]
fw (k + 1) ＝ Ptj ・ fw (k) ＋ Rtj ・ fi (k) (6)
[0071]
Next, the CPU 81 proceeds to step 260, and obtains a steady-state fuel adhesion amount fftj (k + 1) according to the following equation (7). The expression (7) is an expression that is established under the assumption that the fuel adhesion amount is constant before and after fuel injection from the injector 39 (an expression that is established when the engine 10 is in a steady operation state). In other words, the equation (7) indicates that the amount of fuel evaporated from adhering fuel and sucked into the cylinder (= fw (k + 1) · (1-Ptj)) in the steady operation state and the injected fuel are This is an equation obtained from the fact that the amount of adhesion (= fi (k) · Rtj) is equal, that is, the amount of fuel adhesion does not change before and after fuel injection (before and after one intake stroke).
[0072]
In other words, in step 260, steady-state fuel adhesion is used to estimate a steady-state fuel adhesion amount that is a fuel adhesion amount in a steady operation state using the fuel behavior parameters determined in steps 220 and 225 and the fuel behavior simulation model. It is a step which comprises quantity estimation means.
[0073]
[Expression 7]
fwtj (k + 1) = (Rtj / (1-Ptj)) ・ fi (k) (7)
[0074]
Next, in step 265, the CPU 81 stores the steady-state fuel adhesion amount fwtj (k + 1) as the current steady-state fuel adhesion amount fwtj (k) for the next execution of this routine, and in step 295 this routine. Is temporarily terminated. Thereafter, the CPU 81 repeatedly executes the above-described processing every time the crank angle becomes the predetermined angle.
[0075]
As described above, according to the fuel injection amount control apparatus of the first embodiment, the fuel adhesion rate Rtj and the fuel residual rate Ptj adapted in the steady operation state are the instantaneous fuel adhesion amount fw (k). Accordingly, the fuel adhering rate R and the fuel residual rate P are determined more appropriately, so that the fuel injection amount can be determined as a more appropriate amount.
[0076]
Step 240 constitutes a fuel injection amount determining means, Step 250 constitutes a fuel adhesion amount estimating means, and Step 230 and Step 235 (that is, each step in FIG. 3) constitute fuel behavior parameter correcting means. Steps 220 and 225 constitute fuel behavior parameter determining means, step 260 constitutes steady-state fuel adhesion amount estimation means, step 250 constitutes instantaneous fuel adhesion amount estimation means, and step 245 constitutes injection instruction means.
[0077]
(Second Embodiment)
Next, a second embodiment of the fuel injection amount control device according to the present invention will be described. The second embodiment is different from the first embodiment only in that the CPU 81 executes the routines shown in FIGS. 4 to 6 instead of the routines shown in FIGS. Therefore, the following description will focus on differences from the first embodiment, and the same steps as those in the routine of FIG. 2 will be denoted by the same reference numerals, and detailed description thereof will be omitted.
[0078]
The CPU 81 starts the fuel injection control routine of FIG. 4 from step 400 when the crank angle reaches the predetermined angle that is a predetermined crank angle before the intake top dead center of the first cylinder. The CPU 81 executes the same routine as that shown in FIG. 4 for each of the other cylinders.
[0079]
Next, the CPU 81 proceeds to step 205 to step 215, where the intake air flow rate Q, the amount of air KL that will be sucked into the combustion chamber of the cylinder that reaches the intake stroke (here, the first cylinder), and the required fuel amount fc (k In step 405, it is determined whether the value of the attached fuel inflow suppression means execution flag XEKI (hereinafter referred to as “suppression means execution flag XEKI”) is “0”.
[0080]
The suppression means execution flag XEKI indicates that the adhering fuel inflow suppression means (adhering fuel inflow suppression function) is activated when the value is “1”, and the adhering fuel inflow suppression when the value is “0”. Indicates that the means has not been activated. The value of the suppression means execution flag XEKI is determined from the time when the instantaneous fuel adhering amount becomes less than the predetermined threshold value or more than the predetermined threshold value (that is, a part of the fuel adhering to the intake passage constituting member remains in the cylinder state) 6 is operated by the routine shown in FIG. 6 to be described later so as to be set to “1” only for a predetermined time Tth).
[0081]
The adhering fuel inflow suppression means will be described later. For example, the fuel injection timing and the fuel pressure (the pressure of the fuel applied to the injector 39 to inject the fuel so as to inject the fuel only during the period in which the intake air flow rate is large). ) Or a means for increasing the EGR rate (or EGR amount), etc., which makes it difficult for the fuel to adhere to the intake passage constituting member or promotes evaporation of the fuel attached to the intake passage constituting member. Thus, it is means for inhibiting (suppressing) that a part of the fuel adhering to the intake passage constituting member flows into the cylinder in a liquid state.
[0082]
Now, assuming that the value of the suppression means execution flag XEKI is “0”, the CPU 81 determines “Yes” in step 405 and proceeds to steps 220 to 265. Thus, the fuel injection amount fi is obtained from the corrected fuel residual rate P, the corrected fuel adhesion rate R, the instantaneous fuel adhesion amount fw (k), and the inverse model of the fuel behavior simulation model. A quantity fi of fuel is injected from the injector 39 of the first cylinder. Further, the instantaneous fuel adhesion amount fw (k) and the steady-time fuel adhesion amount fwtj (k) are updated. The above operation is the same as the operation of the fuel injection amount control device of the first embodiment except for the determination in step 405. The steady-state fuel adhesion amount fftj (k) is set to a value equal to fw (k) immediately after the value of the suppression means execution flag XEKI changes from “1” to “0”.
[0083]
Next, description will be made assuming that the value of the suppression means execution flag XEKI is “1”. In this case, when the CPU 81 proceeds to step 405, it determines “No” in step 405 and proceeds to step 410, where the value of the instantaneous fuel adhesion amount fw (k) of the first cylinder is smaller than the predetermined threshold value fwth. It is determined from the value whether or not a predetermined threshold value fwth has been reached. As will be described later, when the value of the instantaneous fuel adhesion amount fw (k) of the n-th cylinder (n is a natural number from 1 to 4) becomes smaller than the predetermined threshold value fwth and exceeds the predetermined threshold value fwth, it adheres to the intake passage constituting member. It can be determined that a part of the fuel that has flowed into the nth cylinder remains liquid.
[0084]
Now, if the description is continued on the assumption that the value of the instantaneous fuel adhesion amount fw (k) of the first cylinder becomes smaller than the predetermined threshold value fwth from the value smaller than the predetermined threshold value fwth, the CPU 81 determines “Yes” in step 410. Then, the process proceeds to step 415, and the temperature Theki of the intake passage component (intake passage wall surface) determined based on the average flow velocity u of the air sucked into the first cylinder and the cooling water temperature THW detected by the water temperature sensor 68, Based on the instantaneous fuel adhering amount fw (k) calculated at the time and the table (function) fd, a part of the fuel adhering to the intake passage constituting member flows into the first cylinder as it is in a liquid state. The amount of inflowing liquid fuel fdr (the amount of dripping), which is the amount of fuel that has been discharged, is estimated (fdr = fd (u, Theki, fw (k))). The function fd is determined in advance by experiments and stored in the ROM 82. The average flow velocity u is obtained from the air amount KL, the engine speed NE, and the lift amount of the intake valve 32.
[0085]
Next, the CPU 81 proceeds to step 420 and stores the amount obtained by subtracting the inflowing liquid fuel amount fdr from the instantaneous fuel adhesion amount fw (k) at that time as a new instantaneous fuel adhesion amount fw (k). Then, the CPU 81 proceeds to step 425 and defines the relationship between the engine operating state parameter consisting of the engine rotational speed NE, the air amount KL, and the cooling water temperature THW and the fuel residual rate Ptjed when the adhered fuel inflow suppression function (means) is activated. A table (function) f2 stored in advance in the ROM 82, the current engine speed NE, the air amount KL obtained as described above, and the coolant temperature THW currently detected by the water temperature sensor 68 (current operation state parameter) Based on the above, the residual fuel rate Ptjed at the time of operation of the adhering fuel inflow suppression means is obtained. The table f2 is determined in advance similarly to the table f1. However, when the table f2 is determined, the adhering fuel inflow suppressing means is operated.
[0086]
Similarly, in the subsequent step 430, the CPU 81 stores in advance in the ROM 82 which defines the relationship between the engine rotational speed NE, the air amount KL, the cooling water temperature THW, and the fuel adhesion rate Rtjed when the adhered fuel inflow suppression means is operated. Based on the table (function) g2, the current engine speed NE, the air amount KL obtained as described above, and the cooling water temperature THW detected by the water temperature sensor 68 at the present time when the attached fuel inflow suppression means is activated. Obtain the fuel adhesion rate Rtjed. The table g2 is determined in advance similarly to the table g1. However, the adhering fuel inflow suppression means is also activated when determining the table g2.
[0087]
Next, in step 435, the CPU 81 compares the ratio q (r = r) of the instantaneous fuel adhesion amount fw (k) at the time of operation of the adhered fuel inflow suppression means to the steady state fuel adhesion amount fwtjed (k) at the time of operation of the adhesion fuel inflow suppression means. fw (k) / fwtjed (k)). The steady-state fuel adhering amount fftjed (k) at the time of operation of the adhering fuel inflow suppressing means is an estimated value of the amount of adhering fuel when it is assumed that the engine 10 is in a steady operation state under the operation of the adhering fuel inflow suppressing means. This is obtained in step 465 and step 470 described later. However, the steady-state fuel attachment amount fftjed (k) is set to a value equal to fw (k) immediately after the value of the suppression means execution flag XEKI changes from “0” to “1”.
[0088]
In addition, the instantaneous fuel adhesion amount fw (k) when the adhered fuel inflow restraint means is operated is the obtained fuel adhesion rate Rtjed, the fuel residual rate Ptjed, and the instantaneous fuel adhesion amount fw obtained when the routine was executed last time. This is a value corresponding to the fuel adhesion amount at that time obtained based on (k) and the like, and is obtained in step 455 and step 460 described later.
[0089]
Next, the CPU 81 proceeds to step 440, corrects the fuel residual rate Ptjed when the adhering fuel inflow suppression means is operated based on the ratio q, determines the corrected fuel residual rate P, and adsorbs the adhering fuel based on the ratio q. The corrected fuel adhesion rate R is determined by correcting the fuel adhesion rate Rtjed when the deterring means is operated.
[0090]
More specifically, when the CPU 81 proceeds to step 440, the routine shown in FIG. 5 is started from step 500, and the third predetermined value with the ratio q smaller than “1” (0.9 in this example). In the case of the following, in step 510, the fuel remaining rate Ptjed when the adhering fuel inflow restraint means is operated is corrected by multiplying the fuel remaining rate Ptjed by a coefficient kPed1 smaller than “1” to correct the remaining fuel after correction. The fuel P after the correction is made by correcting the fuel adhesion rate Rtjed by a coefficient kRed1 smaller than “1” so that the fuel adhesion rate Rtjed when the adhering fuel inflow suppression means is operated is reduced in step 515. Determine the adhesion rate R.
[0091]
On the other hand, if the ratio q is greater than or equal to a fourth predetermined value (1.1 in this example) that is greater than “1”, the fuel residual rate Ptjed when the attached fuel inflow suppression means is activated is greater than “1” in step 525. Corrected by multiplying by the coefficient kPed2 to determine the corrected fuel residual ratio P, and corrected by multiplying the fuel adhesion rate Rtjed when the adhered fuel inflow suppression means is activated by a coefficient kRed2 greater than "1" in step 530 The subsequent fuel adhesion rate R is determined.
[0092]
On the other hand, when the ratio q is larger than the third predetermined value and smaller than the fourth predetermined value, the CPU 81 proceeds to step 535 and step 540, where the residual fuel rate Ptjed when the adhered fuel inflow suppressing means is activated and when the adhered fuel inflow inhibiting means is activated. The fuel adhesion rate Rtjed is stored (set) as it is as the corrected fuel residual rate P and the corrected fuel adhesion rate R.
[0093]
Next, the CPU 81 proceeds to step 445 in FIG. 4 via step 595 in FIG. 5, and the inverse model of the fuel behavior simulation model described in step 445, the corrected fuel residual rate P, and the corrected fuel adhesion. The fuel amount (fuel injection amount) fi (k) to be injected into the first cylinder is determined using the rate R, and the fuel of the same fuel injection amount fi (k) is assigned to the first cylinder in step 450 An instruction signal is sent to the injector 39 corresponding to the first cylinder so as to inject from the injector 39.
[0094]
In step 455, the CPU 81 estimates and updates the instantaneous fuel adhesion amount fw (k + 1) according to the equation (fuel behavior simulation model) described in step 455 similar to the above equation (6), and step 460. The instantaneous fuel adhesion amount fw (k + 1) is stored as the current instantaneous fuel adhesion amount fw (k) for the next execution of this routine.
[0095]
Next, the CPU 81 proceeds to step 465 and obtains a steady-state fuel adhering amount fftjed (k + 1) when the adhering fuel inflow suppressing means is operated according to the following equation (8). Equation (8) is an equation that is established under the assumption that the fuel adhering amount is constant before and after fuel injection from the injector 39 (when the engine 10 is in operation of the adhering fuel inflow suppression means), as in Equation (7). (Equation that holds when in steady operation).
[0096]
[Equation 8]
fwtjed (k + 1) = (Rtjed / (1-Ptjed)) ・ fi (k)… (8)
[0097]
Next, in step 470, the CPU 81 calculates the steady-state fuel adhering amount fftjed (k + 1) at the time of operation of the adhering fuel inflow suppression means at the time of operation of the present adhering fuel inflow suppression means for the next execution of this routine. The adhesion amount is stored as fwtjed (k), and this routine is terminated once at step 495.
[0098]
Thereafter, when the crank angle again reaches the predetermined crank angle, the CPU 81 executes the routine of FIG. 4 again. At this time, the value of the suppression means execution flag XEKI remains “1” because the predetermined time Tth has not elapsed since the value of the flag XEKI was changed from “0” to “1”. Accordingly, the CPU 81 proceeds directly to step 425 through step 205 to step 215, step 405, and step 410, and performs processing from step 425 to step 470. Thereby, fuel injection amount control at the time of operation of the adhering fuel inflow suppression means is performed.
[0099]
When the predetermined time Tth has elapsed since the value of the suppression means execution flag XEKI has been changed from “0” to “1”, the value of the suppression means execution flag XEKI has been changed from “1” to “0”. The operation of the adhering fuel inflow suppressing means is stopped. At this time, when the CPU 81 executes the routine shown in FIG. As a result, the fuel injection amount is controlled when the adhered fuel inflow suppression means is stopped.
[0100]
Next, the operation when the adhered fuel inflow suppressing function is operated will be described with reference to the routine shown in FIG. The CPU 81 is configured to execute the routine shown in FIG. 6 every elapse of a predetermined time.
[0101]
Therefore, when the predetermined timing comes, the CPU 81 starts the process from step 600 and determines whether or not the value of the suppression means execution flag XEKI is “0”. The value of the suppression means execution flag XEKI is set to “0” by an initial routine (not shown) when the ignition switch of the vehicle is changed from “off” to “on”.
[0102]
Accordingly, if the description is continued assuming that the value of the suppression means execution flag XEKI is “0”, the CPU 81 makes a “Yes” determination at step 605 and proceeds to step 610 to adhere to the intake passage constituting member. It is determined whether or not any of the instantaneous fuel adhesion amount fw (k) = fwn (k) of the nth cylinder (n is a natural number from 1 to 4) indicating the fuel amount is equal to or greater than a predetermined threshold value fwth.
[0103]
The predetermined threshold value fwth is determined when the instantaneous fuel adhering amount fw (k) = fwn (k) of the nth cylinder indicating the amount of fuel adhering to the intake passage constituting member becomes equal to or larger than the predetermined threshold value fwth. The value is selected such that a state in which a part of the fuel adhering to the intake passage constituting member flows into the nth cylinder in a liquid state is generated.
[0104]
At this time, if the instantaneous fuel adhesion amount fw (k) = fwn (k) of all the cylinders is not equal to or greater than the predetermined threshold value fwth, the CPU 81 makes a “No” determination at step 610 to proceed to step 695. This routine is once terminated. On the other hand, if at least one instantaneous fuel adhesion amount fw (k) = fwn (k) of any cylinder is equal to or greater than the predetermined threshold value fwth, the CPU 81 determines “Yes” in step 610 and proceeds to step 615. Then, the function of the adhering fuel inflow suppression means is activated and the value of the suppression means execution flag XEKI is set to “1”. In step 620, the CPU 81 resets the value of the timer Timer to “0”, proceeds to step 695, and once ends this routine.
[0105]
As a result, the adhering fuel inflow suppressing function is activated. Specifically, the state of the EGR valve 55 is changed from the valve closed state to the valve open state, and EGR gas is introduced into the intake passage and is sucked into the cylinder 21 through the intake valve 32. By introducing the EGR gas, the temperature of the intake passage constituting member rises, so that it becomes difficult for the fuel to adhere to the intake passage constituting member and evaporation of the adhering fuel is promoted. As a result, since the amount of fuel adhering does not become excessive, it is avoided that a part of the fuel adhering to the intake passage constituting member flows into the cylinder 21 in a liquid state.
[0106]
Further, in this embodiment, in step 615, a signal for increasing the fuel pressure (differential pressure Psa) is sent to the fuel pressure adjusting means 39a so that the fuel injection is completed within a short time, and the engine operation is also performed. Fuel is injected so that fuel injection is performed in a period in which the flow velocity of the air sucked into the cylinder 21 is maximized based on the state parameters (engine speed, air amount KL, intake valve timing VT, intake valve 32 lift amount, etc.). Change the injection timing.
[0107]
As a result, the injected fuel rides on the airflow and is sucked more into the cylinder 21, so that it is difficult for the fuel to adhere to the intake passage constituting member. As a result, since the amount of fuel adhering does not become excessive, it is avoided that a part of the fuel adhering to the intake passage constituting member flows into the cylinder 21 in a liquid state.
[0108]
The fuel evaporative emission that causes the vehicle to adsorb the evaporation generated from the fuel system such as a fuel tank to a canister (not shown) and inhales the evaporated emission to the canister into each cylinder and burns it when a predetermined operating condition is satisfied. In the case where a suppression device is provided, in step 615, the same amount of the evaporation may be sucked into each cylinder.
[0109]
In this case, the amount of fuel injected from the injector 39 is reduced by feedback controlling the amount of fuel injected from the injector 39 so that the detected air-fuel ratio A / F of the air-fuel ratio sensor 69 matches the target air-fuel ratio. In addition, since the evaporation is mist-like fuel, it is difficult for the fuel to adhere to the intake passage constituting member. As a result, since the amount of fuel adhering does not become excessive, it is avoided that a part of the fuel adhering to the intake passage constituting member flows into the cylinder 21 in a liquid state. Such large-scale introduction of the evaporation is particularly effective when the engine is cold when the fuel adhesion amount becomes large.
[0110]
When the predetermined time has elapsed, the CPU 81 starts the process again from step 600 and proceeds to step 605. At this time, since the suppression means execution flag XEKI is set to “1” in the previous step 615, the CPU 81 determines “No” in step 605 and proceeds to step 625 to set the value of the timer Timer to “1”. Will only increase.
[0111]
Next, the CPU 81 proceeds to step 630 and determines whether or not the value of the timer Timer has become larger than the predetermined time Tth. At this time, since the value of the timer Timer is smaller than the predetermined time Tth, the CPU 81 makes a “No” determination at step 630 to proceed to step 695 to end the present routine tentatively. Such a process is repeated until the value of the timer Timer is increased every time the predetermined time elapses in step 625 and becomes longer than the predetermined time Tth.
[0112]
When the value of the timer Timer becomes larger than the predetermined time Tth, the CPU 81 determines “Yes” at step 630 when it proceeds to step 630, and stops the operation of the adhered fuel inflow suppression function at step 635. The value of the suppression means execution flag XEKI is set to “0”.
[0113]
As described above, according to the fuel injection amount control apparatus according to the second embodiment of the present invention, the fuel adhesion rate and the fuel residual rate adapted in the steady operation state are determined according to the instantaneous fuel adhesion amount. Since the correction is made, the fuel injection amount can be determined based on a more appropriate fuel adhesion rate and fuel residual rate. Furthermore, the occurrence of a so-called “liquid dripping amount” is predicted and the “liquid dripping amount” is estimated, and the estimated liquid dripping amount is reflected in the instantaneous fuel adhesion amount, and the fuel behavior parameter based on the instantaneous fuel adhesion amount is estimated. Therefore, the fuel injection amount can be made a more appropriate amount.
[0114]
Step 240 and step 445 are fuel injection amount determining means, step 250 and step 455 are fuel adhesion amount estimating means, step 230 and step 235 (each step in FIG. 3), and step 435 and step 440 (each step in FIG. 5). ) Constitutes fuel behavior parameter correction means. Further, Step 220 and Step 225 and Step 425 and Step 430 are fuel behavior parameter determination means, Step 260 and Step 465 are steady-state fuel adhesion amount estimation means, Step 250 and Step 455 are instantaneous fuel adhesion amount estimation means, and Step 245. Step 450 constitutes an injection instruction means.
[0115]
The present invention is not limited to the above embodiment, and various modifications can be employed within the scope of the present invention. For example, in each of the above embodiments, the intake air amount KL is obtained based on the intake air flow rate Ga detected by the air flow meter 61. However, the behavior of the intake air is simulated according to physical laws such as energy conservation laws and mass conservation laws. It is also possible to construct a model to be used and to estimate the intake air amount KL based on the model.
[0116]
In each of the above embodiments, the fuel behavior parameter is corrected based on the ratio r and the ratio q. However, even if the fuel behavior parameter is corrected based on the difference between the instantaneous fuel deposition amount and the steady-state fuel deposition amount. Good.
[0117]
Furthermore, in the second embodiment, the occurrence of liquid sag may be predicted in advance in time. Further, as the adhering fuel inflow suppressing means, a means for changing to an intake pipe shape in which liquid dripping hardly occurs may be employed.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram of a system in which a fuel injection amount control device for an internal combustion engine according to a first embodiment of the present invention is applied to a spark ignition type multi-cylinder internal combustion engine.
FIG. 2 is a flowchart showing a program (routine) executed by the CPU shown in FIG. 1 for fuel injection control.
FIG. 3 is a flowchart showing a program executed by the CPU shown in FIG. 1 to correct the fuel adhesion rate and the fuel residual rate.
FIG. 4 is a flowchart showing a program (routine) executed by the CPU of the fuel injection amount control device according to the second embodiment of the present invention for fuel injection control.
FIG. 5 is a flowchart showing a program executed by the CPU of the fuel injection amount control device of the second embodiment to correct the fuel adhesion rate and the fuel residual rate.
FIG. 6 is a flowchart showing a program executed by the CPU of the fuel injection amount control device of the second embodiment to operate an adhered fuel inflow suppression function.
FIG. 7 is a conceptual diagram for explaining a fuel behavior simulation model.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 ... 4-cycle spark ignition type multi-cylinder internal combustion engine, 20 ... Cylinder block part, 21 ... Cylinder, 31 ... Intake port, 32 ... Intake valve, 39 ... Injector (fuel injection means), 39a ... Fuel pressure adjustment means, 54 ... EGR gas passage, 55 ... EGR valve.

Claims (4)

Fuel injection means for injecting fuel into the intake passage of the internal combustion engine;
Used in the simulation model representing the behavior of the fuel injected from the fuel injection means, and used in the fuel adhesion rate and the simulation model, which is the ratio of the fuel injected from the fuel injection means to the members constituting the intake passage. A fuel behavior parameter including a fuel residual ratio that is a ratio of the fuel adhering to the members constituting the intake passage remaining without being sucked into the cylinder, and the engine when the engine is in a steady operation state. A fuel behavior parameter determining means for preliminarily storing the relationship between the operation state parameter representing the operation state and determining the fuel behavior parameter based on the stored relationship and the actual operation state parameter;
The amount of fuel evaporated from the fuel adhering to the member constituting the intake passage and sucked into the cylinder and the amount of fuel adhering to the member constituting the intake passage from the fuel injected from the fuel injection means Doo is under the assumption that the fuel adhesion amount is constant before and after the fuel injection from the fuel injection means is an amount of fuel deposited on members constituting the same intake passage to become equal, is the determined Steady-state fuel adhesion amount estimation means for estimating a steady-state fuel adhesion amount that is a fuel adhesion amount in a steady operation state using the fuel behavior parameter and the simulation model;
Using the determined fuel behavior parameter and the simulation model, an instantaneous value that is an instantaneous value of a fuel adhesion amount that is an amount of fuel adhering to a member constituting the intake passage for each injection from the fuel injection means An instantaneous fuel adhesion amount estimation means for estimating the fuel adhesion amount;
Fuel behavior parameter correction means for correcting the determined fuel behavior parameter according to a comparison result between the instantaneous fuel deposition amount and the steady-state fuel deposition amount;
Fuel injection for determining a fuel injection amount that is an amount of fuel to be injected from the fuel injection means by applying the corrected fuel behavior parameter and the required fuel amount required for the engine to an inverse model of the simulation model A quantity determining means;
Injection instructing means for instructing the fuel injection means to inject the fuel of the determined fuel injection amount;
A fuel injection amount control device for an internal combustion engine comprising: The fuel injection amount control device according to claim 1 ,
The fuel behavior parameter correction means is configured to correct the fuel behavior parameter so that the fuel behavior parameter becomes larger as the instantaneous fuel attachment amount becomes larger than the steady-state fuel attachment amount. Fuel injection control device. In the fuel injection amount control device according to claim 1 or 2 ,
The instantaneous fuel adhesion amount estimation means adheres to a member constituting the intake passage when the instantaneous fuel adhesion amount estimated using the determined fuel behavior parameter and the simulation model exceeds a predetermined threshold. It is determined that a part of the fuel that has flowed into the cylinder remains in a liquid state, and the amount of inflowing liquid fuel that flows into the cylinder is estimated based on the operating state parameter of the engine, and the simulation is performed with the determined fuel behavior parameter. A fuel injection amount control apparatus for an internal combustion engine configured to estimate an amount obtained by subtracting the estimated inflowing liquid fuel amount from an estimated fuel adhesion amount using a model as a new instantaneous fuel adhesion amount. The fuel injection amount control device according to claim 3 ,
When the instantaneous fuel adhering amount estimation means determines that a part of the fuel adhering to the member constituting the intake passage flows into the cylinder in a liquid state, it adheres to the member constituting the intake passage. A fuel injection amount control device for an internal combustion engine, further comprising attached fuel inflow suppression means that operates to prevent the fuel from flowing into the cylinder in a liquid state.

Images